The present invention relates to a method of dispensing abrasive materials, such as sheets or discs, the abrasive materials being arranged in a bundle so that those sides of the abrasive materials that are provided with an abrasive agent face the same direction.
The invention also relates to an abrasive material dispensed by the above method.
The invention principally concerns a flexibly bendable abrasive sheet product, which hereinafter will be called an abrasive material. The product comprises plates, such as discs or sheets, cut beforehand and coated on one side with an abrasive agent of a varying grit size.
Prior art abrasive materials include, for example, a line of self-adhesive abrasive materials. The abrasive materials are connected to each other along perforated lines, principally tangentially to the periphery of an individual abrasive material. A solution like this is disclosed, for example, in FI 94 603. That side of the continuous abrasive materials which is coated with glue is usually completely covered with a continuous plastic film of a similar shape. This, however, makes it difficult to detach the plastic film from the abrasive material when the material is to be used. Further, the abrasive material must be cut off from large sheets to make it continuous, wherefore a large amount of raw material for abrasive materials is wasted during the production.
To eliminate the above problems, it has been suggested that the abrasive material should be cut off entirely, and the materials should then be attached one after the other to a supporting strip made of paper or to some other elongated means. For example, FI 63 880 teaches solutions where the abrasive material is secured to a supporting strip so that every other abrasive material overlaps every other, and the resultant continuous entity is then rolled up.
From DE 26 26 129 it is also known to arrange the abrasive material on a supporting strip by securing it to the supporting strip along the entire back side.
DE 29 26 340 teaches solutions in which the abrasive materials are fixed to a supporting strip one after the other in a line. The continuous entity is then folded up in a bundle so that every other abrasive material has the side with the abrasive agent facing upward, and every other has the side with the abrasive agent facing downward. A surface provided with an abrasive agent is therefore always facing another surface provided with an abrasive agent in the bundle. To prevent the back sides that are provided with glue and face each other from attaching to each other, the supporting strip must cover the entire back side of the abrasive material provided with glue. Further, each surface provided with glue can be provided with a separate protective covering. If two surfaces provided with glue are allowed to attach to each other, it is extremely difficult to separate them.
The DE publication also discloses an embodiment in which each abrasive material is provided with a protective covering on the back side provided with glue and is connected to a continuous entity by means of separate supporting strips provided with glue. The supporting strip is fixed to the protective coverings of two abrasive materials close to each other. In this embodiment, the abrasive materials are arranged in a bundle so that the front sides provided with an abrasive agent face upward, and each supporting strip is folded in Z form, whereby the free part of the supporting strip principally corresponds to the diameter of the abrasive material in length. This requires a large amount of supporting strip material and a technically advanced feeding line, where the abrasive materials are secured to the supporting strips with acceptable results.
Finally, FI 76 762 teaches solutions in which the abrasive material is fixed to a continuous supporting strip to provide a continuous entity. The entity is then formed into a bundle than can be placed, for example, in a dispenser box. In a solution according to the publication, the abrasive materials in the bundle have the front sides provided with an abrasive agent facing upward, and the supporting strip is passed in loops between the abrasive materials along one side of the bundle. The upper part of each loop of the supporting strip is fixed to the back side of the abrasive material, which is not coated with an abrasive agent, whereas the lower part of each loop of the supporting strip is free between the upper part of the loop and the front side of the abrasive material, provided with an abrasive agent. The supporting strip is thus rendered as short as possible, and yet the supporting materials are efficiently prevented from attaching to each other.
A problem common to all the above solutions is that as the abrasive materials, both sheets and discs, are released from the supporting strip, the supporting strip and the protective coverings are detached and, depending on the implementation, are either left hanging from the dispenser box or are collected on a horizontal surface nearby. Gradually, the supporting strip and the protective coverings form big, disturbing piles or loops in the vicinity of the dispenser box. Such films hanging or lying about are dangerous to health: their surface is slippery, which increases accident risk in the workplace.
The previously known solutions often also require that when the abrasive material is detached from the protective covering, both hands must be used: with one hand one grips the abrasive material and with the other one releases the protective covering.
The problems of the prior art are mainly avoided with the present invention. The abrasive material is much simpler to remove from the dispenser means or detach from the protective covering, and the protective coverings do here not accumulate in undesired amounts on different surfaces, such as workbenches or the floor.
The above problems are solved by the present invention, which has the characteristics disclosed in the claims. A method of the present invention is thus characterized by what is stated in the characterizing part of claim 1.
Further, an apparatus of the present invention is characterized by what is stated in the characterizing part of claim 4.
Many significant advantages are achieved with the method and apparatus of the present invention as compared with the prior art. For example, it is very simple to fasten a tab of the invention to an abrasive material. No complicated feeding lines are thus needed for exact positioning of the tab in respect of the abrasive material. With a solution of the invention, considerably less material is needed for the supporting strip, and so the packaging costs can be minimized.
A tab according to the present invention makes is very easy to detach the abrasive material by gripping it simply with only one hand. This is very important, since the user usually needs the other hand to operate a grinding machine. Although the method is simple, the working space will not be littered at all.
The abrasive material often comprises some kind of attachment means, such as glue or a Velcro fastener, on the back side. It is thus very simple to attach the tab to and detach it from the abrasive material. To prevent the abrasive materials close to each other from attaching to each other, the attachment means preferably comprise a protective covering. When the protective covering is attached to the tab, the tab is easy to detach together with the protective covering, the protective covering remaining in the dispenser means.